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Biomedical subjects

C Fraser

Publications and source records attributed to C Fraser.

At least 127 records · Page 7Linked to original sources
PubMed1980

Evaluation of kerb negotiation in a prototype and standard model wheelchair.

This article outlines an evaluatory study of kerb negotiation in a conventional wheelchair and a prototype diamond configuration, lever articulated wheelchair. The kerb negotiation sequence in both models is presented with the results of tests involving users able to negotiate kerbs (N = 16); users unable to negotiate kerbs (N = 15); and non-wheelchair users (N = 20). Results indicate preferences for the prototype amongst the first group, particularly for kerb descent. Free rolling tests of the loaded wheelchairs over various terrains revealed that while the standard wheelchair invariably turned downhill the prototype was relatively insensitive to loss of direction on sideslopes. A significant number of subjects (P = 0.01, N = 20) found the articulated framework of the prototype reduced the difficulties of self propulsion over rough and cambered surfaces. The prototype was found to possess a smaller turning circle (103 cm to 122 cm) and a longer wheelbase (94.7 cm to 39.7 cm) than the standard model though overall dimensions were broadly comparable. The implications of the prototype wheelbase for manual, attendant and powered propulsion are considered.

Ergonomics↗
PubMed1979

Assessment of the Coag-a-Pet Dual Channel in the routine haemostatic laboratory.

The Coag-a-Pet Dual Channel is an instrument which automatically records coagulation test end-points utilizing a photo-optical clot detection system. The instrument and its operation are described in detail. The capability of the instrument to perform tests of oral anticoagulant control, basic coagulation profiles and one-stage factor assays is assessed. In terms of precision and accuracy, the instrument performs well in carrying out the one-stage prothrombin time, Thrombotest, activated partial thromboplastin time using an automated APTT reagent but not kaolin, and one-stage factor assays. The thrombin clotting time can not be measured on this instrument. The instrument is most suitable for batched repetitive tests, reducing observer error and improving laboratory efficiency.

Blood Coagulation Factors↗
PubMed1979

The Coulter Counter Model S Plus--the shape of things to come.

The Coulter Counter Model S Plus is a 12 parameter haematological analyser designed for service use in haematology laboratories. Eight parameters are standard in current routine haematological practice; the seven parameters generated by the Model S and a platelet count. The method of platelet counting is unique. The remaining parameters are new and comprise the platelet-crit, the mean platelet volume and size distribution measurements for both platelets and red cells. A description of the instrument is given including differences from the Model S. The new parameters are discussed in detail. Instrument precision is assessed in terms of linearity, reproducibility, drift, carry-over and protein build-up. The results of all are impressive. Instrument accuracy is assessed in detail; white cell count, red cell count, haemoglobin concentration and mean corpuscular volume being compared with those values measured by the Model S; the Model S Plus haematocrit is compared with the microhaematocrit and platelet counts with those from the Thrombocounter C/Thrombofuge system. All correlations are very satisfactory. Normal values are defined for the new parameters. Instrument design and function are assessed and reagent consumption quoted. Cell control reagents have been evaluated. A realistic hourly throughput for the Model S Plus is 70-80 samples.

Automation↗
PubMed1979

A laboratory evaluation of Compur M 1000 Miniphotometer and the Compur M 11OO minicentrifuge.

The Compur Miniphotometer and Minicentrifuge are portable instruments designed for rapid estimation of haemoglobin, red cell count and haematocrit on capillary blood. Haemoglobin and haematocrit results correlate well with reference methods. Accurate red cell counts are only obtained when the sample MCV is within the range 83--103 fl, thus restricting the application of this method. The Compur M 1000 Miniphotometer and Compur M 1100 Minicentrifuge have been designed as portable instruments to permit rapid estimations of haemoglobin concentration, red cell count and haematocrit by the non-laboratory worker.

Centrifugation↗
PubMed1978

Dominant inheritance of Scheuermann's juvenile kyphosis.

Familial occurrence of Scheuermann's juvenile kyphosis is well known, but no specific mode of inheritance has been recognized. We describe five families in which the disease seems to follow and autosomal dominant pattern of inheritance.

Adolescent↗
PubMed1978

Sperm motility within the mammalian epididymis: species variation and correlation with free calcium levels in epididymal plasma.

The region within the epididymis where spontaneous sperm motility first appeared and the extent of later motility within that organ, as shown by microscopic observation of undiluted samples, varied with the species. In the rat, mouse, and hamster, little sperm motility was present. In other species, spontaneously motile sperm were obtained from the caput (rabbit) and corpus (bull and man) regions of the epididymis. Samples from the cauda region of the epididymis were found to contain many motile sperm in the rabbit, bull, and especially man, where most of the sperm were intensely motile. There was a correlation between the amount of free calcium surrounding the sperm within the cauda epididymidis of a given species and the level of sperm motility therein. An inverse relationship was also found between the free calcium concentration in the cauda epididymal plasma of a species and the later inducibility of motility in diluted sperm from that species by calcium ion.

Animals↗
PubMed1977

Evaluation of a semi-automated platelet-counting system.

Coulter Electronics Ltd have produced a semi-automated platelet-counting system. Platelet-rich plasma may be obtained either by tube sedimentation or by means of the Thrombo-fuge, the latter being an instrument designed to produce accelerated sedimentation. The instrument is linear over the entire range of platelet counts, and machine reproducibility is good. Comparison of machine-rated with visual counts satisfied statistical evaluation. The technique can be handled by one operator and platelet counts can be achieved at the rate of 30 per hour by both methods although individual counts on the Thrombo-fuge may be obtained in approximately one-quarter of the time required for tube sedimentation. The throughput using the Thrombo-fuge could certainly be doubled were two sample plates supplied. Few problems were encountered during the evaluation and most could be avoided by meticulous technique. Visual counts must be performed when the sample haematocrit is greater than 50%-Discrepant counts have been obtained in patients with white cell counts exceeding 50 X 10(9)/1 and in patients with giant platelets. ESR elevation for any reason does not lead to serious discrepancy in results. The incidence of platelet clumping due to the presence of platelet agglutinins and of microclot formation due to inadequate mixing is probably much higher than is commonly thought, and certainly peripheral blood film scrutiny should never be omitted in patients with low counts. Careful examination of peripheral blood films must be combined with instrument counting for some time lest further causes of discrepant counting emerge.

Blood Platelets↗
PubMed1976

An analysis of the mechanism of local anesthetic inhibition of platelet aggregation and secretion.

Aggregation induced in human platelets by thrombin (TH), collagen (COLL) or the Ca++ ionophore, A23187, was blocked by dibucaine and tetracaine. COLL-induced aggregation was blocked at lower concentrations of anesthetics (0.01-0.5 mM) than TH- or A23187-induced aggregation (0.2-2.0 mM). The rate and magnitude of the release of adenosine diphosphate, Ca++ and serotonin was also decreased by anesthetics. Secretion due to COLL, but not to TH, required extracellular Ca++ and was accompanied by increased uptake of 45Ca which was inhibited by local anesthetics. A23187-induced secretion was partially dependent upon external Ca++ and was accompanied by increased 45Ca uptake. Anesthetics increased 45Ca uptake when added before, but not after, A23187. This effect can be explained by postulating that the anesthetics prevent the release of an internal pool of Ca++, thereby affecting the Ca++ gradient between platelet cytoplasm and extracellular fluid. Platelets degramulated, but not aggregated, by exposure to TH in the presence of ethylene glycol bis(beta--aminoethyl ether)-N, N'-tetraacetic acid and plasmin were isolated by sepharose gel filtration. Such platelets did not aggregate with COLL or TH, but did aggregate with A23187-an effect blocked by local anesthetics. Thus platelet aggregation and secretion are independent Ca++-requiring processes, each of which is inhibitable by local anesthetics, presumable by blocking Ca++ influx or the mobilization of intracellular Ca++ stores.

Adenosine Diphosphate↗
PubMed1975

Mothers' speech to children of four different ages.

This study reports analyses, in terms of five different measures, of the speech on two standard tasks of 32 middle-class mothers to their children aged 1 1/2, 2 1/2, 4, and 6 years. Sex and birth order of child were not found to be related to mothers' speech. On four of the measures, both task and age of child had strongly significant effects. In general, with increasing age of child, mothers spoke more, in longer and grammatically more complex utterances, with greater diversity of vocabulary. The differences in speech addressed to 1 1/2-year-olds and that addressed to 2 1/2-year-olds were particularly marked.

Age Factors↗
PubMed1975

The effects of processing of barley-based supplements on rumen pH, rate of digestion of voluntary intake of dried grass in sheep.

1. In one experiment the effect on rumen pH of feeding with restricted amounts of whole or pelleted barley was studied. With whole barley there was little variation in rumen pH associated with feeding time, but with pelleted barley the pH decreased from about 7-0 before feeding to about 5-3, 2--3 h after feeding. 2. The rate of disappearance of dried grass during incubation in the rumens of sheep receiving either whole or pelleted barley was studied in a second experiment. After 24 h incubation only 423 mg/g incubated had disappeared in the rumen of sheep receiving pelleted barley while 625 mg/g incubated had disappeared when it was incubated in the rumen of sheep receiving whole barley. 3. The voluntary intake of dried grass of lambs was studied in a third experiment when they received supplements of either 25 or 50 g whole or pelleted barley/kg live weight 0-75. At the high level, pelleted barley reduced intake of dried grass by 534 g/kg but whole barley reduced it by only 352 g/kg. The digestibility of acid-detergent fibre was reduced more by pelleted barley than by whole barley but there was a tendency for a small increase in digestibility of the barley due to processing. 4. The implications of these findings on supplementation of roughages with cereals are discussed.

Animal Feed↗
PubMed1975

Human platelet secretion and aggregation induced by calcium ionophores. Inhibition by PGE1 and dibutyryl cyclic AMP.

Ca2+, Mg2+-ionophores X537A and A23,187 (10(-7)-10(-6) M) induced the release of adenine nucleotides adenosine diphosphate (ADP, adenosine triphosphate (ATP), serotonin, beta-glucuronidase, Ca2+, and Mg2+ from washed human platelets. Enzymes present in the cytoplasm or mitochondria, and Zn2+ were not released. The rate of ATP and Ca2+ release measured by firefly lantern extract and murexide dye, respectively, was equivalent to that produced by the physiological stimulant thrombin. Ionophore-induced release of ADP, and serotonin was substantially (approximately 60%) but not completely inhibited by EGTA, EDTA, and high extracellular Mg2+, without significant reduction of Ca2+ release. The ionophore-induced release reaction is therefore partly dependent upon uptake of extracellular Ca2+ (demonstrated using 45Ca), but also occurs to a significant extent due to release into the cytoplasm of intracellular Ca2+. The ionophore-induced release reaction and aggregation of platelets could be blocked by prostaglandin E1 (PGE1) or dibutyryl cyclic AMP. The effects of PGE1, and N6, O2-dibutyryl adenosine 3':5'-cyclic monophosphoric acid (dibutyryl cAMP) were synergistically potentiated by the phosphodiesterase inhibitor theophylline. It is proposed that Ca2+ is the physiological trigger for platelet secretion and aggregation and that its intracellular effects are strongly modulated by adenosine 3':5'-cyclic monophosphoric acid (cyclic AMP).

Adenosine Diphosphate↗